#include <stdio.h>
int main() {
    float score;
    printf("请输入成绩：");
    scanf("%f", &score);

    // 校验成绩范围
    if (score < 0 || score > 100) {
        printf("成绩输入错误！\n");
        return 1;
    }

    char grade;
    // 按分数区间判断等级
    if (score >= 90) grade = 'A';
    else if (score >= 80) grade = 'B';
    else if (score >= 70) grade = 'C';
    else if (score >= 60) grade = 'D';
    else grade = 'E';
    printf("等级：%c\n", grade);
    return 0;
}